The very strong el Niño which has been driving global weather over the past year is now showing signs of weakening (I’ve been following it since 2014). The monthly diagnostic discussion released by NOAA’s Climate Prediction Center on 10th March reported that surface temperatures in the tropical Pacific have moderated slightly and deeper water temperatures have fallen significantly – signs that it is coming to an end, although it remains strong at present. Models generally predict a flip into la Niña conditions by late summer or fall; however, just as the start of this el Niño was delayed by nearly a year, its termination may also surprise us. It has proved to be very close to as strong as the 1997-98, one if not stronger.
The local winter has been strongly affected with generally mild temperatures except when the polar vortex managed to break out and plunge south. Thus we had a couple of periods in February when it was bitterly cold, reminiscent of last year, but mild and sunny days in between. My lake did not finally freeze over until late on 9th January, and is already threatening to thaw. (Meaning that it has opened up for a few days in the center, but is now frozen over again – won’t be long now.) So far we have had negligible run-off, a consequence of the milder winter with much melting of snow during the warmer times and little snow pack build-up. In fact, we are just completing a winter that will likely become a lot more common as we move on into this century and CO2 levels in the atmosphere rise further. The local Muskoka Watershed Council has just released a report describing the most likely climate here at mid-century and discussing its likely impacts, and actions we need to take. And this winter is a harbinger.
While the focus of most people discussing recent weather has been squarely on the el Niño, all that the el Niño has done is to temporarily amplify the warming of our climate, which continues inexorably as we continue our releases of greenhouse gases. Climate warming may even be responsible for the considerable strength and persistence of this el Niño, but, regardless, once we subside into la Niña next year, the overall long-term warming will have progressed and the world will be that much closer to any tipping points that are out there. In one sense, el Niño now gives us a glimpse ahead to the climate that is coming. It’s not a pretty sight.
While I tend to notice the effects of el Niño on my local weather, el Niño has had far larger, more severe impacts in parts of the world a little closer to the tropical Pacific. Winter has been substantially milder than usual in western North America, and there has been some significant rain in California. Coral reefs around the world have been impacted by warm water and have been bleaching one by one. And Arctic sea ice has been slow to form this winter.
This el Niño is killing lots of coral
Severe coral bleaching near Heron Island, southern Great Barrier Reef this February.
Photo © XL Catlin Seaview Survey.
As I write, scientists coordinated by the James Cook University-based Coral COE (for coral reef research center of excellence) have been running a massive aerial survey of bleaching reefs in the northern third of the Great Barrier Reef. While data collected in the aerial surveys will provide a rapid, region-wide assessment of the extent of bleaching, field teams are being directed to specific locations based on the aerial surveys to collect more detailed analyses of extent of the bleaching, and extent of coral mortality. Australia is one of very few tropical countries with the capacity to mount such a large monitoring effort, and the results, when compared to data from previous bleaching events should help answer some critical questions about the capacity of corals to adapt to warming seas.
On 19th March, Dr. Terry Hughes of James Cook University, the scientist leading the current monitoring effort, posted this message on coral-list, an e-mail list serving the global coral reef research and management community:
“Unfortunately, the northern section of the Great Barrier Reef is now severely bleached. In preparation for the risk of coral bleaching, we convened the National Coral Bleaching Network last November to plan a coordinated response across Australia’s research and reef management community. The ARC Centre has allocated approximately $1million to respond to the 2016 bleaching on the GBR and elsewhere on tropical and sub-tropical reefs around Australia. We’re focusing on the GBR, the Coral Sea, coastal and offshore reefs in WA, and sub-tropical reefs on both the east and west coast.
“In the next few days, I’ll conduct ten aerial transects (3-6 hour flights) throughout the 1000km region between Cairns and PNG that is most severely impacted by bleaching. Thereafter, we plan to expand these surveys to cover elsewhere in the GBR Marine Park south of Cairns. To eliminate observer-bias, the aerial surveys in Queensland will be conducted by myself and James Kerry.
“We have relocated JCU’s research vessel, the Kirby, from Townsville to Cairns, and it will operate from today in the northern GBR and Torres Strait for the next month. It will be joined shortly by two other vessels from the ARC Centre and the Australian Institute for Marine Science (AIMS). The GBR research stations, on Lizard and Orpheus Island in particular, are also fully engaged in the bleaching event. We are working very closely with the GBR Marine Park Authority and other management agencies in QLD, NSW and WA.
“Thankfully, the southern GBR looks to be in the clear.”
This is a major monitoring effort, being mounted through the efforts of the research community in Australia, rather than by the management agency of the federal Australian government, although, in fairness, the government has put some new money into the project.
One of the critical as yet unanswered questions about coral bleaching is whether repeated events (as reefs can expect as the seas continue to warm) will cause corals to adapt, becoming more tolerant of high temperatures. Some scientists believe that ‘of course’ this will happen, but others are concerned that the pace at which the oceans are warming is very fast compared to the generation time of corals, and that this will make significant adaptation very difficult to achieve.
(Adaptation is an evolutionary change, and it requires opportunities for individual organisms to be stressed and for the more tolerant ones to then be more successful at reproducing so that their genes become the dominant ones in the population. If the stress – the bleaching – is happening too frequently, animals may simply get killed from repeated bleaching long before they reproduce. One complication that keeps scientists arguing about this possibility is that the coral animals are in a symbiosis with single-celled dinoflagellates of the genus Symbiodinium as their partners. The dinoflagellates have much shorter generation times and perhaps they could adapt to the warmer water. After all, bleaching is really the collapse of this symbiosis, and just as it takes two to tango, it takes two to end a partnership.)
The bleaching risk for north-eastern Australia as projected by NOAA Coral Reef Watch on 28 March 2016. Not surprising that extensive bleaching is now being documented on the northern Great Barrier Reef. Figure courtesy NOAA Coral Reef Watch.
One goal of the present monitoring effort will be to look critically for evidence that corals are proving more resistant to bleaching this time than those same corals were when they last experienced significantly warmed water in 1998 and in 2002. Maybe there will be some good news to report on this front, to stack up against the bad news of yet more coral mortality. Incidentally, Terry Hughes’ final comment refers to the fact that the waters were warming up and down the 2500 km length of the Great Barrier Reef, and severe bleaching was expected along its length. However, the last few weeks have been predominantly cloudy further south on the reef, keeping surface waters moderated, and now, with the end of summer approaching, a general cooling down is anticipated. Great news, but it tells us something important when we realize we have to hope for overcast weather to prevent wholesale damage to coral reefs.
The bleaching now going on in Australia is just the latest in a series of bleaching events around the world that has been occurring since the el Niño started in earnest early in 2015. On 8th October 2015, NOAA’s Coral Reef Watch program declared the third global coral bleaching event on record had commenced during the summer of 2014 and was likely to continue into early 2017. The first reports of significant bleaching came from Hawaii, both around the main islands and at reefs in the remote Papahanaumokuakea Marine National Monument in the north-western Hawaiian chain, in August 2014. Significant bleaching was also reported that year in the Marianas, Guam, the Marshalls, Kiribati, and Florida. Then bleaching conditions moved to the southern hemisphere, and reports of bleaching came in from the Solomon Islands, Vanuatu, Tuvalu, Fiji and the Samoas. By early 2015, there were reports of bleaching from the British Indian Ocean Territory, south of the Maldives, and there was further extensive bleaching in Hawaii during summer of 2015, the first reported occurrence of two successive years of bleaching in Hawaii. Since then, as the el Niño continued and the seasonal cycle moved locations for warm water around the globe, there have been reports of bleaching from many Pacific locations, from the Indian Ocean, and from the Caribbean. Fiji had back-to-back bleachings in early 2015 and early 2016. Now, as I write, scientists are surveying the damage across hundreds of kilometers of the northern Great Barrier Reef. And NOAA has announced that this will be the longest continuous global coral bleaching event ever.
Lest it be forgotten, it has even been necessary for Australian scientists to point out that the el Niño is only exacerbating and hastening the damage that will inevitably occur to coral reefs as global temperature continues its climb. While I am trying to leave politics out of this post, the need to point out that bleaching is a response to rising ocean temperatures, not a response to a routine weather oscillation that has been going on, presumably, for hundreds or thousands of years, arises simply because the Australian government currently is seriously schizophrenic when it comes to protecting the Great Barrier Reef. Yes, the reef must be protected, but yes, the Australian coal mining and exporting industry (which creates dirty CO2-emitting fuel, while its export degrades reef waters) must be encouraged and supported. One might think that politicians who get to form national governments in mature nation states would be able to follow short chains of logic. Judging by what I see on Twitter or in the media, the current Liberal-Country Party leadership of Australia lacks that capacity.
Meanwhile back in the Arctic
The el Niño has also been impacting sea ice formation in the Arctic, and this year’s ice accumulation is running well below average for the last several years. The latest data from the National Snow and Ice Data Center (NSIDC) at University of Colorado, Boulder, shows a total area of 14.9 million km2 of ice present on 25th March, compared to ~15.3 million km2 in a typical year. One very likely consequence is that we are likely to see a record low level of ice remaining when September comes around.
Arctic sea ice extent as of 25th March 2016 (blue line) is running 2SD lower than the average extent over 1981 to 2010. This may well mean another very low coverage following next summer’s melt. We’ll check back in September. Image courtesy of the National Snow and Ice Data Center, University of Colorado, Boulder.
What does this generally low level of sea ice mean? Well, it has no impact on sea level rise, because this is floating sea ice, not continental ice. And, yes, it does bode well for those cruise ship operators itching to have their ships wallowing through the Arctic filled with tourists eating in the restaurants, exercising their arms at the slot machines, wallowing in the pool (I’ve found it quite rare to see a non-wallower in a cruise ship pool), and just occasionally peering out to sea to see the Arctic in all its splendor. Who knows … maybe Royal Dutch Shell will reverse its most recent decision and once more announce plans to prospect for oil in Arctic waters; if they do not, some other resource companies will, and if not oil, it will be some other resource that they believe they can extract from deep cold Arctic waters with ‘minimal environmental impact’.
Melting of Arctic sea ice is encouraging a ramp-up of national territorial claims, flag plantings, and minerals exploration. Will we act wisely and first learn sufficiently about this ecosystem to manage our exploitation of it? That would be a first! Image © Wednesday-Night
But what does the lack of ice mean for the environment? Perhaps the greatest change is the greater albedo of open water compared to ice, and therefore, the greater rate of warming of Arctic waters because less sea ice is around. Here we have a positive feedback loop, because while it may have been an el Niño that has made this a low-ice year, the fact that the ice is less prevalent means rate of warming now increases, and if warming increases enough, we will not need any more el Niños to give an extra push. The Arctic will become ice-free in a few more years. And, if I understand the Polar vortex sufficiently, a warmer Arctic Ocean means more instability in the weather, and climates in mid-northern latitudes that become ever more variable. (That’s a polite way of saying that eastern North America can expect to see lots of winters as unpredictably crazy as this one has been – especially south of here in Virginia and North Carolina and Alabama and Mississippi – or more so.)
Ice is Amazing
I’ve recently been pondering the incredible unlikeliness of life. On a cosmic level, we know of nowhere in this universe that is within reach of our relatively puny transport, and that we could go to and survive outside a controlled environment system such as a space suit, an orbiter, or a sealed, pressurized surface module. Forget images of the astronaut, standing, legs apart, six feet tall, dressed head to toe in his gloriously white, sleek, Calvin Klein-created space suit, helmet under one arm, and his blond hair blowing in the wind on a strange planet with two moons. Even apart from the sexism, it ain’t likely to happen, because planets like that do not exist in our corner of the universe.
Never mind life like us, we have not yet been able to find conclusive evidence of any type of life anywhere in the universe beyond our small planet. Life surely exists elsewhere, even intelligent life, because our universe is impossibly big. But life is incredibly unlikely, improbable. Some people see God in that improbability; I just see the utterly unexpected wondrousness of the natural world. The very rarity of life elsewhere is a sign of how wonderful our home planet really is; teeming with life, in every habitat no matter how severe, even deep within the rocks of the Earth, or clustered at those scaldingly hot, chemically noxious, hydrothermal vents deep in the ocean. You’d think we might value it more.
Tube worms and a fish at a hydrothermal vent prove that life can occur anywhere on our planet. Photo © WGBH educational Foundation.
And water has a lot to do with life. This simple molecule is essential for life on this planet, and is a major component of every living thing. Among the many important, and unusual, properties of water are the fact that its solid form, ice, is less dense than the liquid, and the fact that the process of melting or freezing involves such a high latent heat. In fact, compared to other common substances, water has the highest specific heat, at one calorie per gram, the highest latent heat of fusion, 80 calories per gram, and the highest latent heat of evaporation, 540 calories per gram. These unusual properties mean that the oceans can contain an immense quantity of heat, that the melting of ice or the evaporation of water requires a further immense quantity of heat, and that any ice which forms will float on the surface of a body of water. If just the latter feature were to be replaced with the more usual situation (the solid form is more dense than the liquid), freezing on lakes or the ocean would take a lot longer because the entire mass of water would have to be lowered to the freezing point before any freezing occurred, but then the entire mass would freeze, condemning aquatic creatures to an interestingly restricted existence. Spring and summer thawing might never extend deeper than the upper few dozen meters of water, and aquatic life would have to evolve to live in ponds of liquid water on the surface of a permanently frozen block of ice, if it evolved at all.
But, I digress. That is not how the world is. Ice is lighter than water, sea ice floats at the surface, and ice is whiter and more reflective than open water. It is these unusual physical properties of water which underlie the paper by James Hansen of Columbia University Earth Institute, and colleagues there, at the Goddard Institute for Space Studies, and at a number of other environmental and climate research centers, now published in Atmospheric Chemistry and Physics, volume 16, on 22nd March. I had earlier discussed this paper when it was posted on-line for public peer-review, an unusual procedure and perhaps a sign of the times in scientific research. It was first on-line last July, and there have been numerous comments, queries and corrections to it during the intervening months. Still, the final version is scarcely changed in overall thrust, and undoubtedly a stronger product as a result of the scrutiny. Perhaps the biggest changes between the initial and final manuscripts have been a change of title, and a reorganization of the sequence of topics considered.
Originally titled “Ice Melt, Sea Level Rise and Superstorms: Evidence from Paleoclimate Data, Climate Modeling, and Modern Observations that 2°C Global Warming is Highly Dangerous”, the paper has become “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2oC global warming could be dangerous.” “is highly” is a value-judgement, and “could be” is the more circumspect way in which scientists usually signal their value judgements. The reorganization of subject matter makes the sequence of arguments easier to follow and appreciate. There are numerous additional citations to document claims, but no substantive retraction of what was originally reported, and the abstract is substantially longer and more detailed (a tacit recognition of the fact that too many of us read only the abstract of most papers we scan). Hansen’s message can be summed up as follows (all extracted from the abstract):
“The modeling, paleoclimate evidence, and ongoing observations together imply that 2oC global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield (1) cooling of the Southern Ocean, especially in the Western Hemisphere; (2) slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss; (3) slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region; (4) increasingly powerful storms; and (5) nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years. These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments. We discuss observations and modeling studies needed to refute or clarify these assertions.”
I find this article no less alarming than I did when it referred to a 2oC warming as ‘highly’ dangerous. Effectively, Hansen and colleagues are arguing that evidence to date is consistent with the hypothesis that we have already passed, or are very close to, a tipping point at which melting of glaciers becomes essentially unstoppable, and that, over a period that will likely go into the 22nd century, sea levels will rise substantially and the temperature differential between the tropics and poles will become greater, leading in turn to much more violent weather than we now experience. Do we really want to test this hypothesis by continuing to emit greenhouse gases?
And so, there is a major coral bleaching event under way that is currently damaging the reefs of the northern Great Barrier Reef. It is the third global-scale bleaching event in history, occurring 6 years after the second, which occurred 11 years after the first. This time, some reefs are experiencing serious bleaching two years in succession. There will be more, and each one seems to take out substantial areas of reef permanently (NOAA’s current estimate for this one, once completed, is about 15 thousand km2 of reef globally, about 6% of the world’s total, to be killed). The cause of this worsening situation is our emissions of greenhouse gases.
Coral bleaching is not just bad for corals. These fish were seen recently in their bleached anemone host near Lizard Island, Great Barrier Reef. Photo © Justin Marshall
These same emissions are largely responsible for the record low level of sea ice in the Arctic, and Jim Hansen’s paper provides convincing evidence for the suggestion that our emissions have already, or perhaps almost, brought the glaciers of the world to a tipping point beyond which melting will continue until sea level is several meters higher than today some 50 to 150 years from now. Does the global community really want to go to that future?
With these messages from the Arctic and the tropics, the Paris agreement reached less than four months ago seems very inadequate indeed, and the near cessation of efforts by governments to move beyond Paris, or even to bring their emissions into compliance with their commitments made there, must be seen as truly alarming. Every country that produces significant greenhouse gases – certainly including the top ten in 2015: in rank order China, USA, India, Russia, Japan, Germany, Korea, Canada, Iran, Brazil, and Indonesia – should be making substantial efforts to cut them much faster than committed to at Paris. In Canada, the Trudeau government’s first budget, released on 22nd March, had several components that will aid the shift towards reduced carbon pollution – tax measures to encourage investment in clean technology, significant funding to ensure a more effective National Energy Board, and Canadian Environmental Assessment Agency, and a $2 billion Low Carbon Economy Fund. However, the budget missed the opportunity to more aggressively phase out coal or oil, and failed to signal a determination to go beyond the climate commitments made at COP21 (commitments shaped by the previous government and widely condemned as inadequate). As for Australia, just a few positions down below the top ten emitters, difficult as it may seem to some politicians, that coal has got to stay in the ground.